The present invention relates to bicycle chains, of the type comprising a large number of chain links hinged together and consisting of pairs of elongated plates, parallel to each other and a certain distance apart, arranged alternately externally and internally, so as to define outer links, comprising outer chain plates, alternating with inner links, comprising inner chain plates, each outer link being hinged on opposite sides to two adjacent inner links by means of pins secured at their ends to the plates of the outer link.
A bicycle chain according to the known technology is illustrated in FIGS. 1 and 2 of the appended drawings. FIG. 1 shows a portion of the chain, comprising outer links A alternating with inner links B, mutually hinged about axes of articulation C. FIG. 2 shows partially in section and on an enlarged scale, the connection between an outer link A and an inner link B. The outer link A is made up of two outer plates D. Corresponding to each axis of articulation C, the two outer plates D have coaxial holes E within which the ends of an articulating pin F are secured with an interference fit. Pin F supports, with articulation, two inner plates G constituting an inner link B. The inner plates G have coaxial portions H in the form of bushes, on which a roller I is mounted, free to rotate. A bicycle chain is arranged as a closed loop and engages one of the gears associated with the crank axle of the bicycle (chain ring) and one of the pinions associated with the rear wheel of the bicycle. When we wish to remove the chain, for example for the purpose of adding or removing chain links, or for lubricating the chain, it is necessary for one of the pins F to be removed partially, as shown in the left part of FIG. 2 of the appended drawings. As a rule, the pin is not removed completely, but remains secured and projecting from one of the outer plates D, as shown in FIG. 2. When it is necessary to reassemble the chain, an inner chain-link is arranged between the two plates D and then connected to them with articulation, returning pin F to the original position and fitting the said pin with interference in the respective hole provided in plate D shown at the top in FIG. 2.
Recent developments in the design of the pinion assembly associated with the rear wheel of the bicycle have led to the production of assemblies with an ever larger number of pinions. In order to minimize the axial dimensions of the assembly, the pinions are being made thinner and thinner, and closer together, which in consequence makes it necessary to manufacture drive chains that are narrower and narrower, so as to ensure that when the chain is in engagement on a pinion it does not interfere on one side with the adjacent pinion. It is also essential that with the chain in its assembled state, the articulating pins of the chain should have zero or at any rate very reduced projection relative to the outer plates of the chain. Therefore, when carrying out the operation of dismantling and then reassembly of the chain, care must be taken that pin F shown on the left in FIG. 2 is put back in a correctly assembled state, where it has minimum projection to the outside of the outer plates of the chain. Proper execution of this operation can prove difficult when the chain has a very small transverse dimension.
It should also be pointed out that special links (or xe2x80x9cfalse linksxe2x80x9d) for bicycle chains have already been proposed, and these have the purpose of permitting quick and correct assembly of the chain (cf. U.S. Pat. No. 5,362,282).
The purpose of the present invention is to provide a special link for bicycle chains, which permits easy and quick execution of the operation of assembly of the chain, ensuring correct execution of the assembly operation, even with chains with a very small transverse dimension, and with relatively simple and inexpensive means.
With a view to achieving this aim, the object of the invention is a special quick-connection link for a bicycle chain of the type indicated above, characterized in that the said special link comprises a pair of outer plates, the first of the said outer plates being equipped, to correspond to at least one of the two articulations of the link, with a tubular articulating pin, having a first end secured to the said first outer plate, and able to receive on itself and support, in hinged fashion, an inner chain-link, with the end of the tubular pin opposite the said first end that projects beyond the said inner link and is received in a hole in the second outer plate, the said special link comprising in addition a locking element that can engage on the said tubular pin, to prevent separation of the said second outer plate from the tubular pin.
In a preferred embodiment, the special link according to the invention is provided with the aforesaid tubular pin and with the respective locking element corresponding to each of its two articulations.
Still in the case of the aforementioned preferred embodiment, the locking element is a quick-coupling peg, which goes into the respective tubular pin and which is provided with a head to prevent unthreading of the second outer plate from the tubular pin, the said quick-coupling peg and the said tubular pin being provided with means for mutual engagement for axial restraint of the peg in the tubular pin.
In one example of application, the aforesaid means for mutual engagement comprise a circumferential rib projecting from the inside surface of the tubular pin and an annular surface for stopping the peg, defined by a middle portion of the peg with reduced diameter.
Again in the case of the aforesaid example of application, the peg has a conical point capable of interacting with a bevelled edge of the aforesaid circumferential rib to facilitate the engagement of an end portion of the peg in addition to the aforesaid rib.
On account of the aforementioned characteristics, once the chain has been dismantled in the conventional way, the chain can be assembled by replacing an outer link of the chain with a special link according to the invention.
In the case of the example of embodiment cited above, the mutual engagement of the stop peg in the respective tubular pin is irreversible, so that once the special link is fitted, the chain can be dismantled again in the conventional manner corresponding to a conventional link and then refitted with the addition of a new special link.
Of course, it is possible to use any number of special links according to the invention in one and the same chain and it is indeed possible to envisage a chain comprised solely of special links according to the present invention.